Magnetic modified non-sintered fly ash filter material, preparation method and application thereof

Abstract

The application discloses a kind of magnetic modified sintering-free fly ash filter materials, preparation method and application.The filter material is the porous matrix loaded with magnetic modifier;Wherein, the porous matrix is made from the raw materials with the following weight parts by sintering-free process: secondary fly ash 60-70 parts, steel slag powder 10-15 parts, 42 cement 10-15 parts;Water-cement ratio 55-60%.The application realizes the high-value utilization of fly ash and steel slag and other industrial solid waste by optimizing the raw material ratio and preparation process, and the preparation process does not need high-temperature sintering, has the advantages of low energy consumption, simple process, etc., and the prepared magnetic modified filter material has good physical properties and pollutant removal capacity, and can be widely used in wastewater treatment field, has significant environmental and economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional materials and water treatment technology, specifically relating to a magnetically modified non-sintering filter material made from industrial solid waste fly ash and its preparation method, as well as the application of this filter material in nitrogen and phosphorus adsorption in wastewater. It is particularly suitable for biological contact oxidation processes and constructed wetland systems in the treatment of urban sewage and industrial wastewater. Background Technology

[0002] Currently, widely used fillers in water treatment (such as ceramsite, zeolite, and activated carbon) generally suffer from problems such as high energy consumption, insufficient adsorption performance, and poor biocompatibility. Traditional sintered ceramsite requires high-temperature preparation above 1200℃, resulting in high energy consumption and carbon emissions. Furthermore, its effectiveness in reducing total phosphorus (TP) and ammonia nitrogen (NH4) is questionable. + The adsorption rate of (-N) is typically below 40%, with low porosity (<30%) and small specific surface area (<5m²). 2 The surface inertness of fly ash leads to a long microbial biofilm formation period (>30 days) and low biofilm abundance (relative abundance of Proteobacteria <40%). Meanwhile, fly ash, as a major solid waste from coal-fired power plants, has a global annual emission exceeding 1 billion tons, but its comprehensive utilization rate is less than 50%. Existing utilization methods (such as brick making and cement production) still rely on high-temperature sintering (800-1000℃), failing to completely solve the high energy consumption problem. Furthermore, the products have limited functionality and cannot effectively adsorb pollutants, while direct landfilling carries the risk of heavy metal (such as As and Pb) leaching. Although magnetic materials (such as Fe3O4) can improve the pollutant adsorption capacity and microbial enrichment effect of fillers, existing magnetic modification technologies (such as physical mixing methods) suffer from drawbacks such as easy detachment of magnetic particles (wear rate >8%), a decrease in specific surface area (20-40%), and high cost (commercial magnetic fillers cost 3000-5000 yuan / ton), limiting their large-scale application. Therefore, developing an environmentally friendly water treatment packing material with low energy consumption, high adsorption capacity, and excellent biocompatibility has become a key issue that the industry urgently needs to address. Summary of the Invention

[0003] To overcome the above-mentioned defects, the purpose of this invention is to provide a magnetically modified non-sintering fly ash filter material, its preparation method, and its application.

[0004] To achieve the above objectives, the present invention provides a magnetically modified non-sintering fly ash filter material, wherein the filter material is a porous matrix loaded with a magnetic modifier;

[0005] The porous matrix is ​​made from the following raw materials by weight using a non-sintering process: 60-70 parts of secondary fly ash, 10-15 parts of steel slag powder, and 10-15 parts of No. 42 cement; with a water-cement ratio of 55-60%.

[0006] Furthermore, the magnetic modifier is Fe3O4 particles, which are loaded onto the surface of a porous substrate by electrochemical deposition. The main phases include CaCO3, SiO2, Al2O3 and iron oxides.

[0007] Furthermore, the secondary fly ash, steel slag powder, No. 42 cement, foaming agent, and water-cement ratio of 60% must be thoroughly stirred for 120 seconds after mixing.

[0008] Furthermore, the foaming agent is an animal protein foaming agent. At a maximum dilution ratio of 1:30, 500 ml of the foaming agent solution produces foam with a foaming ratio of 24.26 times and a settling rate of 7.12% after 1 hour. The foaming agent is added at a ratio of 1.5% of the total dry weight of the material.

[0009] Furthermore, the iron oxide comprises a Fe3O4 and / or γ-Fe2O3 cubic spinel structure, with iron on its surface in the form of Fe... 2 + and Fe 3+ Mixed valence states exist.

[0010] To achieve the above objectives, the preparation method of the magnetically modified non-sintering fly ash filter material of the present invention includes the following steps:

[0011] (1) Mix fly ash, steel slag powder and cement in proportion, add water and animal protein foaming agent, and stir until a uniform slurry is formed.

[0012] (2) The slurry was poured into a mold and steamed at 70°C for 12 hours to obtain a porous matrix;

[0013] (3) Fe3O4 particles were loaded onto the substrate surface by electrochemical deposition and dried to obtain magnetically modified filter material.

[0014] Furthermore, the parameters of the electrochemical deposition method include: Fe 2+ / Fe 3+ Solution concentration 0.1-1 mol / L, current density 10-50 mA / cm² 2 The deposition time is 30-120 minutes.

[0015] Furthermore, the apparent density of the magnetically modified non-sintering fly ash filter material is 754.4 kg / m³. 3 The water absorption rate in 1 hour is 33.67%, the sum of the breakage rate and wear rate is 4.64%, and the specific surface area is 11.23 m². 2 / g, porosity ≥43%.

[0016] To achieve the above objectives, the magnetically modified, non-sintered fly ash filter material of the present invention, when used in water treatment, achieves removal rates of 76.18% and 68.24% for TP and NH3-N in wastewater, respectively, before magnetic modification. After magnetic modification, the removal rates of TP and NH3-N in water treatment increase to 84.56% and 74.43%, respectively.

[0017] The filter media obtained by this invention has a strength of 754.4 kg / m³. 3 The apparent density is 11.23m. 2 With a specific surface area of ​​ / g and a porosity of ≥43%, its main phases include CaCO3, SiO2, Al2O3, and Fe3O4 and / or γ-Fe2O3 with a cubic spinel structure. The surface iron element is mainly Fe. 2+ and Fe 3+ The filter media exhibits excellent pollutant removal performance, with removal rates of 76.18% and 68.24% for TP and NH3-N respectively before magnetic modification. After magnetic modification, the removal rates of TP and NH3-N are further improved to 84.56% and 74.43% respectively. This invention achieves high-value utilization of industrial solid wastes such as fly ash and steel slag by optimizing the raw material ratio and preparation process. The preparation process does not require high-temperature sintering and has the advantages of low energy consumption and simple process. The magnetically modified filter media has both good physical properties and pollutant removal capacity, and can be widely used in the field of wastewater treatment, with significant environmental and economic benefits. Attached Figure Description

[0018] Figure 1 XRD patterns of Fe3O4 and magnetically modified fly ash filler;

[0019] Figure 2(a) Scanning electron microscope image of the unmodified product;

[0020] Figure 2(b) Scanning electron microscope image after magnetic modification. Detailed Implementation

[0021] The following is combined with Figure 1 Figures 2(a) and 2(b) provide a detailed description of the embodiments of the present invention.

[0022] As an embodiment of the present invention, the magnetically modified non-sintering fly ash filter material of the present invention uses secondary fly ash (60-70 parts by weight), steel slag powder (10-15 parts by weight), and No. 42 cement (10-15 parts by weight) as matrix materials. A water-cement ratio of 60% is adopted, and an animal protein foaming agent with excellent foaming properties is added (foaming ratio 24.26 times, 1-hour settling rate 7.12%). After thorough mixing for 120 seconds, it is cast into shape and then steam-cured at 70°C for 12 hours to prepare a porous matrix. Finally, an electrochemical deposition method (Fe...) is used. 2+ / Fe 3+Solution concentration 0.1-1 mol / L, current density 10-50 mA / cm² 2 It was prepared by loading Fe3O4 magnetic particles (with a deposition time of 30-120 min).

[0023] As an embodiment of the present invention, the preparation method of the magnetically modified non-sintering fly ash filter material of the present invention includes the following steps:

[0024] Using secondary fly ash (60-70 parts by weight), steel slag powder (10-15 parts by weight), and No. 42 cement (10-15 parts by weight) as matrix materials, a 60% water-cement ratio was adopted, and an animal protein foaming agent with excellent foaming properties was added (foaming ratio 24.26 times, 1-hour settling rate 7.12%). After thorough mixing for 120 seconds, the mixture was poured into molds and then steam-cured at 70℃ for 12 hours to prepare a porous matrix. Finally, an electrochemical deposition method (Fe) was used. 2+ / Fe 3+ Solution concentration 0.1-1 mol / L, current density 10-50 mA / cm² 2 The filter media was prepared by loading Fe3O4 magnetic particles (with a deposition time of 30-120 min); the resulting filter media has a strength of 754.4 kg / m³. 3 The apparent density is 11.23m. 2 With a specific surface area of ​​ / g and a porosity of ≥43%, its main phases include CaCO3, SiO2, Al2O3, and Fe3O4 and / or γ-Fe2O3 with a cubic spinel structure. The surface iron element is mainly Fe. 2+ and Fe 3+ Mixed valence states exist.

[0025] As an embodiment of the present invention, the application of the magnetically modified non-sintering fly ash filter material exhibits excellent pollutant removal performance. Before magnetic modification, the removal rates of TP and NH3-N reach 76.18% and 68.24%, respectively. After magnetic modification, the removal rates of TP and NH3-N are further improved to 84.56% and 74.43%, respectively. The present invention achieves high-value utilization of industrial solid wastes such as fly ash and steel slag by optimizing the raw material ratio and preparation process. The preparation process does not require high-temperature sintering and has the advantages of low energy consumption and simple process. The magnetically modified filter material obtained has both good physical properties and pollutant removal capacity, and can be widely used in the field of wastewater treatment, with significant environmental and economic benefits.

[0026] Example:

[0027] First, accurately weigh 70 wt% of secondary fly ash, 15 wt% of steel slag powder, and 15 wt% of No. 42 cement as matrix materials. Add deionized water at a water-cement ratio of 60%, and add 1.5% of animal protein foaming agent by dry weight of the total materials (this foaming agent, at a dilution of 1:30, can prepare stable foam with a foaming ratio of 24.26 times and a 1-hour settling rate of 7.12% in 500 ml solution). Add the above raw materials to a mixer and mix thoroughly for 120 seconds to form a uniform slurry, then pour it into a mold for shaping. Place the shaped blank in a 70℃ steam curing chamber for 12 hours to obtain a porous matrix. Subsequently, perform magnetic modification using electrochemical deposition with 0.5 mol / L Fe... 2+ / Fe 3+ The mixed solution is an electrolyte, and the current density is controlled at 30 mA / cm². 2 Fe3O4 magnetic particles were uniformly loaded onto the substrate surface after a deposition time of 60 minutes. The resulting product was then dried at 60℃ for 24 hours to obtain the finished filter media. The apparent density of this filter media was measured to be 742.6 kg / m³. 3 The water absorption rate is 33.27% in 1 hour, the sum of the breakage rate and wear rate is 4.21%, and the specific surface area reaches 11.65 m². 2 / g, porosity 48.2%; XRD analysis shows that its phase composition includes CaCO3, SiO2, Al2O3 and Fe3O4 / γ-Fe2O3 with a cubic spinel structure; in water treatment applications, this filter media achieves removal rates of 83.12% and 71.53% for TP and NH3-N, respectively, which are significantly improved compared to the unmodified version (71.53% and 65.22%), demonstrating excellent pollutant removal performance. In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0028] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A magnetically modified, non-sintering fly ash filter material, characterized in that, The filter media is a porous matrix loaded with a magnetic modifier; The porous matrix is ​​made from the following raw materials in parts by weight using a non-sintering process: 60-70 parts of secondary fly ash, 10-15 parts of steel slag powder, 10-15 parts of No. 42 cement, foaming agent, and a water-cement ratio of 55-60%. The magnetic modifier is Fe3O4 particles, which are loaded onto the surface of a porous substrate by electrochemical deposition. The main phases include CaCO3, SiO2, Al2O3 and iron oxides. The secondary fly ash, steel slag powder, No. 42 cement, foaming agent, and water-cement ratio of 55-60% must be thoroughly stirred for 120 seconds after mixing. The foaming agent is an animal protein foaming agent. At a maximum dilution ratio of 1:30, 500 ml of the foaming agent solution produces foam with a foaming ratio of 24.26 times and a settling rate of 7.12% after 1 hour. The foaming agent is added at a ratio of 1.5% of the total dry weight of the material. The iron oxide comprises a cubic spinel structure of Fe3O4 and γ-Fe2O3, with iron on its surface in the form of Fe²⁺. + and Fe³ + Mixed valence states exist.

2. A method for preparing the magnetically modified non-sintering fly ash filter material according to claim 1, characterized in that, Includes the following steps: (1) Mix fly ash, steel slag powder and cement in proportion, add water and animal protein foaming agent, and stir until a uniform slurry is formed; (2) The slurry was poured into a mold and steam-cured at 70°C for 12 hours to obtain a porous matrix; (3) Fe3O4 particles were loaded onto the substrate surface by electrochemical deposition and dried to obtain magnetically modified filter material; The parameters of the electrochemical deposition method include: Fe² + / Fe³ + Solution concentration 0.1-1 mol / L, current density 10-50 mA / cm², deposition time 30-120 min.

3. The method according to claim 2, characterized in that, The apparent density of the magnetically modified non-sintering fly ash filter material is 754.4 kg / m³. 3 The water absorption rate in 1 hour is 33.67%, the sum of the breakage rate and wear rate is 4.64%, the specific surface area is 11.23 m² / g, and the porosity is ≥43%.

4. The application of the magnetically modified non-sintering fly ash filter material according to claim 1 in water treatment, characterized in that, Before magnetization modification, the removal rates of TP and NH3-N in wastewater as a water treatment filter media reached 76.18% and 68.24%, respectively. When magnetically modified for water treatment, the removal rates of TP and NH3-N increased to 84.56% and 74.43%, respectively.

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